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The purpose of this thread is to explain how to both physically hook up the connections between your computer and AVR/Pre-Pro to get started with REW (Room EQ Wizard) and to share information on the proper use of REW including proper techniques for both measuring and interpreting graphs, what you should be looking for in each graph, how to fix problems using room treatment, speaker placement, listener placement, and other tweaks, both before and after EQ, and delve more into topics not often talked about which when dealt with properly can drastically change (for the better) your listening experience to become true audio nirvana.

Some topics will include:

Not relying on only the Frequency Response to determine whether or not, "you're there" when it comes to setting up and measuring your system. The Modal Ringing which is shown in a Spectral Decay plot (Waterfall Graph) is much more important to look at and treat via bass traps and subwoofer placement for the lower frequencies than a simple frequency response and in the middle and upper frequencies, the ETC is very important to verify early reflections are either deflected or absorbed from your listening position. The frequency response is very basic and only one of many tools to show you the true response of your system.

How to treat your room. Where to begin? You must first pick an acoustical model. Just throwing up "fuzzy stuff" (Insulation, bass traps, acoustical panels, etc) can be more harmful than good to the end result. You must first start with a plan. We'll define the most common models and how best to achieve them in your room.

Individual participation sharing your graphs - This is the perfect place for it. We'd love to see what you've accomplished in your room, along with photos and a journal explaining each step you took to get to the end result. I learned a ton in the beginning by imitating others and what they did. Patterns will start to emerge and folks that do not wish to spend hours a day, every day for months or years will get a good sense of what to do and not do.

Different types of Mic's, discussions about the Mini-DSP UMIK Mic and Dayton UMM-6 Mic, installation, integration with REW, etc.

This list will be added to as time permits and as visitors make suggestions for common topics.

I hope this becomes an active thread and we have a lot of discussion on the implementation and use of REW that will not only show us how our systems are performing but will motivate us to do something about the problems in the response.

PLEASE only post in this thread on topic and understand that derailments from trolls, folks trying to sell their wares (constantly plugging certain acoustical products) and bickering/arguing will NOT be tolerated.

This is a safe place for people to learn and all forum rules are in full effect with a zero tolerance policy on breaking the rules.

Having said that, I look forward to a fun and active discussion as the newest version of REW now includes support for ASIO (HDMI Support to measure all 8 channels) and USB Mics for an extremely simplified setup which should attract many more folks wanting to trust but verify what their "Automated" Room Correction Systems have done and I hope this becomes the place for support and "how-to's."

To get us started, below are some FAQ’s, do’s, do not’s, how’s, and why’s on a variety of subjects that both come up often and unfortunately, don’t come up often enough.

Q: Did I configure my graphs properly? Are the horizontal and vertical scales set properly? What are the various settings in the "Controls" panel for each type of graph?

A: You will use the “Controls” and “Limits” function located at the top right of your screen in REW most often. There are different settings for different graphs and different reasons for each one which is explained below.

Frequency Response – You need to set the top and bottom limits to fit the “unsmoothed” frequency response graph on your screen, but with as much resolution as possible. It is easy to make any graph look “good” and by not showing much resolution almost anything can be made to look flat. Pretty graphs are not what we’re after though. A good way to start is to look at the highest peak on the frequency response.

Let’s say it’s 85db for example. Click “Limits” and set the “Top” limit to no more than 90db so the highest point in the graph will be close to the top of your screen but you have a bit of room to spare with nothing spilling over the top. Then for the bottom, set it to where the bottom of the longest spike, which will always be in the upper frequencies past about 2khz or so is shown and you’ve maxed out your resolution. Then verify that on the left hand side of your screen that the graph lines are in increments of 5db. Less than this is too much resolution and more isn’t enough.

The standard is 5db and is what most people are used to looking at. If you see a lot of comb filtering and are measuring an untreated room and without EQ you may find it impossible to get within these parameters on the upper end of the frequency spectrum. As long as you show the highest peak and have about 60db showing below this, it’s okay if you can’t quite fit all the vertical lines/comb filtering on your screen, but make certain you don’t clip the top/peaks off. As for the left and right limits, these will differ depending on what you’re working on or sharing at the time. You can set the “Left” limit to 20hz for instance, and the “Right” limit to 20000hz for instance, to show the entire audible range of the frequency response, but more commonly you’ll either be measuring the effects of bass trapping and want to focus more on the lower frequencies or measuring the effects of different placement of acoustical panels, speaker placement, listener placement, etc, and be focusing more on mid and high frequencies. To show more resolution you can set the left and right limits to just show 10hz to 300hz for example to get the maximum resolution in your graphs for modal frequencies.

TIP: ALWAYS MEASURE FULL RANGE, IE: 10HZ – 20000HZ AS YOU CAN MANIPULATE THE GRAPHS LATER TO ONLY SHOW THE PORTION YOU WANT. NEVER LIMIT MEASUREMENTS TO ONLY 10HZ – 200HZ FOR EXAMPLE, AS IT ONLY TAKES A FEW MORE SECONDS TO DO A FULL MEASUREMENT SWEEP AND THAT DATA CAN BECOME INVALUABLE LATER.

Waterfall aka Cumulative Spectral Decay – This is a much more important graph than a simple frequency response and one we’ll surely be talking about it more detail. It’s also much more important we get this one right when sharing it with others as just like the frequency response, almost any waterfall graph can be made to look good, but we want the real scoop and not pretty graphs to sell acoustical treatments.

This graph shows us frequency against time (there is a lot more to the explanation than this, but we’ll start here) and is used mainly to view lower frequencies, below 300hz or so. Recommended graph settings for left/right limits are 20hz – 300hz. If you have a subwoofer that goes lower than 20hz with substantial output, it is still not necessary to show frequencies below 20hz unless you have a very large room (longer than 30ft or more) that can modally support these lower frequencies. This graph is used to look at modal decay and can show ringing and why you may have one-note bass. It can also be used to show what your Room EQ software has done and if it’s made any of the ringing “worse” as sometimes happens. As for the “Top” and “Bottom” limits, you want to follow the same advice as above in the frequency response, showing 60db. You need to take all of your measurements with as little noise in the room as possible, but this measurement especially needs to show 60db above the noise floor, or as close to it as possible. For instance, the average American living room has an approximately 40db noise floor. That means your measurements need to be taken at about 100db which is very loud.

TIP: WEAR EAR PLUGS WHEN TAKING MEASUREMENTS.

Taking measurements at this level will do a few things. First, and most importantly, it will get you above the noise floor so you can get accurate decay times and secondly it will show you how flat your subwoofer truly is down at 15-20hz when played at this volume. Lot’s of people brag they have “Flat” sub response down to 10hz, but at what level? 60db? 70db? You cannot hear or feel 10hz at 70db but at 100db if you have a sub-woofer(s) that can perform with reasonable distortion at this level, you have something to be quite proud of, along with a literally shaking foundation. If you cannot run a measurement at 100db and you cannot get your noise floor below 40db your measurements aren’t totally invalid, but you may not be able to get the full picture or capture your true in room decay times to 60db.

TIP: THE RT60 TAB/MEASUREMENT IS USELESS FOR SMALL ACOUSTICAL SPACES, WHICH IS EVERY “HOME” IN THE WORLD. THERE IS NO RT60 IN SMALL ROOMS, WHICH IS WHAT WE’RE DISCUSSING ON THIS THREAD. WE WILL NOT DISCUSS RT60 FURTHER AS IT IS MEANINGLESS, HOWEVER, DECAY TIMES IN MODAL FREQUENCIES ARE VERY IMPORTANT AND IS A BIG TOPIC ALONG WITH A HARD PROBLEM TO SOLVE.

In short, the goal for decay times for an average sized living room or dedicated home theater in the USA is somewhere in the range of 300ms to 500ms for frequencies between 500hz and 20khz and a good rule of thumb is not more than 450ms for modal frequencies; those frequencies below Fs. The ultimate goal is to make the entire spectrum not differ more than 10% full range, but that’s hard to do because unless you know the tricks of the trade (which we’ll talk about on this thread) you will find that as you add more bass trapping to get the decay times down for the lower frequencies, you overdeaden/overdampen the upper frequencies. There are several workarounds for this and we’ll go into much more detail in the thread on how to compensate for this.

ETC – Envelope/Energy Time Curve – The settings for this graph aren’t as precise, but for what we’ll mostly be looking at, I recommend showing from 0 – 40ms unless your room is longer than 30’ or so and again, show at least 60db on the left side. What we want to see here depends on the acoustical model you’ve chosen. However, a good rule of thumb, to begin with at least, is to have no spikes above -20db between 0ms and 20ms. Anything under 20db is fine. There are several nuances to this though. All the spikes should decay as evenly as possible and be spaced as evenly as possible. Having no spikes above -20db (from reference set as 0db) is effectively anechoic, or “without echo” and this is a good thing, to a point. However, this initial time delay (sometimes referred to as ITG or initial time gap) needs to be terminated at some point or you’ll have a rather dull, dead, and lifeless sounding room. A good termination point is somewhere past 15ms and no more than about 25ms. This should be as close to or above -12db as possible to terminate this initial time delay gap. This is critical in a LEDE/RFZ room and we’ll go into much more detail in the thread on the how-to. The ETC is often very misunderstood and overlooked, and this is very unfortunate as it is the most critical of all tools and by it being time based you can easily use it to calculate and solve for most other problems, so this is my personal pick for a desert island graph where if I could only pick one…

Q: How should the speakers be configured before taking these measurements? Do I measure one speaker at a time for ETC? Does the waterfall need all subs as well as the main speakers in the measurement? Is Audyssey on or off? Do I take measurements only at the MLP, or at several spots in the room?

A: There are different configurations for different types of measurements. You should always measure the full spectrum starting with the lowest frequency your subwoofer(s) will play to and going up to 20000hz no matter what you will be analyzing. Using graph limiting, explained above, you can look at whatever range you wish, but it’s good to have all the data available.

Frequency Response – Measure L+Sub then measure R+Sub and overlay the two. NEVER measure together for this. It will show a lot of comb filtering and not give you true results. TIP: Comb Filtering doesn’t actually exist!! It’s simply the name we give to the visual effect we see on graphs! When you overlay the L+Sub and R+Sub graphs they should not deviate by more than +/- 2db from each other. If they do, you need to alter the speaker placement and/or listening position until there is as little deviation between the L and R speakers as possible.

TIP: DO NOT RELY ON ROOM CORRECTION SOFTWARE FOR THIS AND ALWAYS MEASURE WITHOUT ROOM CORRECTION ENGAGED!

Waterfall – This is the only measurement where you do actually want to measure both the Left and Right speakers along with all subwoofers, together. You’re looking at the combined response in the modal region on this graph, so you need every speaker playing that will be playing frequencies below 300hz at the same time, which is the Left, Right, and Subs.

ETC – See Frequency Response – Same thing applies – Overlay Left and Right and if spikes (equal to reflections) exist in one speaker but not the other, at the same point in time before 20ms or so (early reflections) then you don’t have symmetry and at the very least need to reflect, diffuse, or absorb the “different” spikes/reflections.

You will want to take two sets of measurements each time you make a change. The great thing about REW is you can look at many different graphs, set them up to view different parameters at a time, IE: Full range or limited range (as long as you always ‘measure’ full range to begin with) and manipulate the graphs to suit your needs any time in the future. Each time you measure, you should ALWAYS first measure with NO EQ then, without moving the mic, measure WITH EQ.

Then you should move the mic a few inches to the left, and repeat, then to the right, repeat, up, down, etc. You can then look in the bottom left hand corner of your screen and click the “Average” button which will spatially average all of your measurements together. So you always want to take several measurements around your MLP and both with and without EQ for comparison and to see exactly what that EQ is really up to.

TIP: ALWAYS NOTATE YOUR MEASUREMENT BEFORE PROCEEDING TO THE NEXT MEASUREMENT. TRUST ME, YOU WILL “NOT” REMEMBER THE DETAILS LATER AND WITHOUT PROPER NOTES ON EACH MEASUREMENT, THE IMPORTANT MEASUREMENT CAN BECOME MEANINGLESS QUICKLY.

TIP: IF YOU WANT MORE RESOLUTION/DATA ON YOUR SCREEN, AT THE TOP OF THE MEASUREMENT NOTES ON THE LEFT HAND SIDE OF YOUR SCREEN, CLICK “COLLAPSE” AND THE AREA DESCRIBING EACH MEASUREMENT WILL SHRINK WHILE THE ACTUAL GRAPH WILL EXPAND. IF YOU WANT TO READ YOUR NOTES MORE CLEARLY LATER, SIMPLY CLICK THE SAME BUTTON AGAIN, WHICH WILL NOW READ, “EXPAND.”

Q: What do the waterfall graphs show? Does the Waterfall show any resonances that need to be looked at, or does the graph show something that is "good enough"?

A: Teaching you to understand how to interpret all the graphs in REW is one of the main goals of this thread.

In essence, the waterfall graph, if configured properly as detailed above, will show you certain frequencies that take longer to decay than others. If, for instance, 40hz “rings” out to 700ms but most of the rest of the frequencies stop ringing (this looks like mountains coming forward/towards you on your monitor) at 300ms, then you have a modal problem at 40hz and need to treat it with passive EQ, IE: Bass traps.

TIP: IF YOU CANNOT SEE YOUR MOUNTAINS FULLY DECAY ON YOUR MONITOR AND INSTEAD, YOU ONLY SEE “FLAT” PEAKS THEN YOU HAVEN’T SET THE “CONTROLS” TAB PROPERLY, LOCATED NEXT TO LIMITS. YOU WANT TO SET YOUR CONTROL TABS “TIME RANGE (MS) TO WHATEVER LEVEL IS NECESSARY TO SEE THE LONGEST MOUNTAIN PEAK FULLY DECAY INTO THE FLOOR. DEPENDING ON HOW STRONG THE PEAK IS AND WHETHER OR NOT YOUR ROOM IS TREATED, THIS COULD EASILY EXCEED 700-800MS. AS YOU ADD MORE TRAPS OR MOVE SPEAKERS/SUBS AROUND, THIS WILL GET SMALLER, AND THE GOAL IS TO GET ALL THE FREQUENCIES WITHIN 10% OR AS CLOSE AS POSSIBLE TO EACH OTHER AND BE ABLE TO EVENTUALLY VIEW EVERYTHING ON THE GRAPH AT NO MORE THAN 600MS MAXIMUM, PREFERABLY CLOSER TO 400MS.

Q: Once I know what I am looking at, what are the various methods to address the problems? Should I go out and buy a roll of pink fluffy?

A: Once you understand that there will certainly be peaks in the ETC, ringing in the waterfall, and uneven frequency response both before and after Room EQ software is engaged, you have to determine where to begin.

The best place to begin is with moving your sub(s) and listening position, even just a few inches at a time, being sure to measure and notate the exact locations of each speaker and your listening position on each measurement.

TIP: BE SURE TO “SAVE ALL MEASUREMENTS” IN REW – THIS WAY THE .MDAT FILES CAN BE SHARED WITH OTHER USERS AND YOU CAN RECALL THEM LATER.

Then, once you’ve found the best speaker and listening position, the best place to begin as far as treatment is concerned is with bass trapping. Although there are several different types of traps, IE: Helmholtz, Membrane, Slotted, etc, the most common (and affordable) type you will see for sale is of the fuzzy breed also referred to as “Pink Fluffy.” This is basically household insulation like R30 or specialty insulation most often used by HVAC contractors for air conditioning duct work, commonly referred to as “OC 703” or “OC 705.” These types of insulation/bass traps are resistive and worked based on the relationship between the Gas (air) Flow Resistance and the thickness.

TIP: 4” “BASS TRAPS” COMMONLY SOLD FOR $75 - $250EA ARE “NOT” BASS TRAPS!!! AT BEST THEY ARE BROADBAND ACOUSTICAL PANELS.

A common question is, “Is thicker better?” NOT ALWAYS. For instance, a common design touted amongst the forums is the “SuperChunk.” This is commonly prescribed as a minimum of 17” x 17” x 24” triangles stacked up in the corners of your room. Unfortunately, while this does work, it would work much better and be much cheaper if a much lower GFR material, for instance R-30 which is approximately 5000 Rayl/s were used instead of the commonly used OC 703 (or variant) which is somewhere above 30000 Rayls.

We’ll talk much more about this on the thread, but a good rule of thumb is, if you have the space, thicker traps (from about 8” and thicker) work better with lighter, fluffier, common insulation like R-30 attic insulation but if you have less than 8” to work with, OC 703 or Roxul Safe N Sound (20,000 Rayl/s or so and now available at most Lowe’s stores) with a higher GFR work better in the lower frequencies.

It’s all relative and there is no one size fits all answer, but I assure you that thicker/bigger is not always better. For the folks that spent a lot of money on OC 703 to make triangles/SuperChunk style, pull it out…Use it for broadband panels, and replace with “Pink Fluffy” as 17” thick traps made from OC 703 (36,000 Rayl/s or so) or heaven forbid someone that went all out and used OC 705 (60,000 Rayl/s or so) and made the 24” thick (34” wide) larger variant have simply wasted a lot of money. While these “traps” will perform, they won’t perform nearly as well as a properly sized trap vs its GFR will.

A great tool which is free, easy to use, and requires no download/installation to see exactly how your traps perform (you can model 4 different sizes/types of trap at the same time to see what will work best with the space and budget you have) is at - This is a very powerful Porous Absorber Calculator, is very accurate, and is what I use in designing/building Porous traps (traps made from insulation).

TIP: ANY “BASS TRAP” YOU WILL SEE FOR SALE BETWEEN $75 AND $200 IS NOTHING MORE THAN INSULATION WRAPPED IN CLOTH. IF YOU USE THIS FORUM, USE THE CALCULATER MENTIONED ABOVE, AND HAVE EXTREMELY BASIC DIY SKILLS, YOU CAN VERY EASILY BUILD ALL OF YOUR OWN ACOUSTIC PANELS AND BASS TRAPS FOR ABOUT 5% TO 10% OF THE COST OF PURCHASING, PLUS THEY WILL BE CUSTOM FITTED AND YOU’LL HAVE LEARNED A LOT. IF, HOWEVER, YOU HAVE MORE MONEY THAN TIME, WELL… YOU PROBABLY AREN’T READING THIS TO BEGIN WITH.

I plan to add to this post as other topics, FAQ’s, etc come up, so please check back to the first page often as there will be updated information appearing here as time permits and if requested, or as long as the thread stays active.

Thanks for this thread. I just downloaded REW last week and am planning on diving into it. No experience with it whatsoever. Speaking of mics...I can confirm my HTPC does not see the mic included with my Pioneer VSX52 receiver for MCACC. Interesting. So Im looking for a mic now

This post will eventually contain the FAQ for this thread. In the meantime I strongly recommend that everyone download AustinJerry's Step By Step Guide to setting up and using this version of REW, with a USB mic and HDMI connection to the AVR. The Guide is essential reading for those with little or no REW experience and contains step by step instructions on how to configure Windows, how to set up REW and how to take basic measurements and make graphs - all fully illustrated with relevant screen shots.

The 'standard' for graphs to be posted to this thread is as below. This is the same standard as used at HTS, home of REW and is designed to ensure compatibility and easy cross-referencing of posted graphs.

The preferred axis for ALL subwoofer graphs is:

VERTICAL = 45dB-105dB
HORIZONTAL = 15Hz-200Hz.

The preferred axis for full range graphs is:

VERTICAL = 45dB-105dB
HORIZONTAL = 15Hz-25,000Hz.

These values are defaulted into REW, but can easily change and must be set back to these axis for posting graphs.

Smoothing:

Smoothing should not be applied to subwoofer graphs. For full range graphs, 1/6-octave smoothing is beneficial.

The HTS graph standard is as below - you will see that they require logarithmic graphs, not linear:

Set the graph type by clicking the Freq Axis button.

With thanks to HTS for the information in this post.

Note to Thread Starter:

Jason - I can't use the second post of course as it is 'yours'. It maybe possible for you to ask a Mod if he can change the username to mine on that post. Otherwise I will use this post.

Edit: below is a rough and ready copy/paste of every relevant post from the Audyssey thread:

Hey guys,

I use REW and honestly, it couldn't be easier or more robust.

The newest version, which is of course also free, now has support for Plug-N-Play USB Mics.

You can get an individually calibrated USB Mic from Cross Spectrum Labs for about $99 shipped and there is no pre-amp, phantom power, etc needed.

So there is only one piece of equipment to buy, the mic, and it's plug-n-play, the software is free, and as mentioned in a post above, you can take one measurement, one time, and then manipulate it any way you want to get any data out of it you want and until you learn (there are several threads that go into detail about how to read and interpret each chart/graph) you can also share the measurement file so more experienced folks can manipulate it and analyze it with standard graph settings that most of us use.

You can literally plug the mic in now, tell REW which USB Mic you're using, and take a measurement in less than 5 minutes for less than $100 with an individually calibrated mic.

IMHO it doesn't get any better than this and it's by far the cheapest and most robust solution.

While it is true that REW generates the signal internally, meaning you will have to hook your computer/laptop up to any available stereo input on your AVR, you will not need to use an external CD/DVD Player and CD/(DVD??) like you do with Omnimic/RTZ so that pretty much cancels each other out as far as I'm concerned.

There are no other "black boxes" needed. You will NOT need a full duplex sound card because you aren't using the sound card's mic input and speaker/line output at the same time, as you'll be using the USB Mic. So the built-in sound card that every PC/Laptop has works fine. (Using it this way myself on a cheap laptop)

Yes, the output/jack on the sound card is 1/8" stereo mini and Yes, the input on the AVR is RCA, but that is taken care of by a $3.00 1/8" to RCA Splitter/Y-Adapter that I bet most of you already have.

The Mic is USB and there are a few options, both of which are under $100 shipped and that should be all you need, unless you need to get the $3.00 adapter to go from 1/8" stereo plug to RCA Jack. You can actually get these at Monoprice for $1.00 or so!

The first MIC Option, and the one I recommend, is the Dayton UMM-6 USB Mic calibrated individually, by a human being (who has his own very high quality/expensive calibration mic/rig and a lot of experience) at Cross Spectrum Labs.

CSL no longer ship calibrated mics worldwide. Those not in the USA might consider the UMIK-1 which, I believe, is available worldwide.

If you are a member of HTShack, which is where most of the support for REW is and where JohnAV, the writer/owner of REW hangs out, simply put your username in the notes when you order and he'll give you $10.00 off if you order before Jan 1st! After Jan 1st, he will still give you $5.00 off!

I've found out a few more things I'd like to share. First, this mic is the same or very similar as what is offered with Omnimic and you can also purchase it directly from PartsExpress.

However, the Mic's that come with your Omnimic and this Dayton UMM-6 Mic, which you can also purchase directly from PartsExpress for about $5.00 less are NOT "truly" individually calibrated by a human, nor do they come with calibration files for 0, 45, and 90 degrees, polar responses, etc, which can come in very handy once you learn more about taking measurements and if you get serious about it and acoustics/improving your room.

The EMM-6 and a few others (old mic that a lot of people use which requires Pre-Amp/Phantom Power) also states it's calibrated and you simply go to the web-site, enter your serial number, then get a cal file however, when CSL compared their truly individually calibrated mics they found up to 5db difference!

So, please understand that the mics you think (because you were told so!) are calibrated really are not and do not match with true individual calibrations. Some are closer than others, but you won't know unless you get them calibrated.

CSL and PartsExpress both purchase these wholesale from Dayton and PE simply charges a few dollars less but doesn't do anything other than sell you the mic as it came from Dayton, however, CSL actually calibrates each mic individually at 0, 45, and 90 degrees, and does this all while charging about the same price!

There is another option, too. Mini-DSP just came out with a USB MIC but you purchase it directly from them. They ship from Hong Kong, but surprisingly, it only takes a few days and everyone over at HTShack has had a good experience so far. So since CSL doesn't get a good break on them wholesale, they don't offer them directly/individually calibrated aren't truly individually calibrated from Mini-DSP, but supposedly are very close. You could always purchase this MIC if it's your preference and send it in to CSL to have them calibrate it of course. I "think" that's around $50-$60 or so??

The latest version of REW, just posted last week, has a drop down menu selection where you can select the Mini-DSP mic (linked to a few posts back) and it's as simple as selecting the mic you're using and running measurements!

GIK Acoustics has a good video tutorial on their web-site on using REW and how to take a measurement to get started and of course there is lots of help on AVS and HTShack.

I helped AustinJerry awhile back in interpreting his results and making some recommendations and would be more than willing to help each and every one of you with anything you need from setting it up, which honestly couldn't be easier, to performing measurements, to helping you understand what they mean and what to do about them.

I love this stuff so much and spend several hours per day 7 days a week between AVS and Gearslutz which is where I have learned so much about acoustics and room treatment.

I have personally been able to get my dedicated theater within +/- 4db with NO Audyssey unsmoothed, and within +/-2 db with 1/3rd smoothing all the way from 20hz-20khz but have realized over the last year or so that frequency response is NOT at all, not even close, to being what is very important.... It's the modal decay times in the low frequencies and the ETC in the upper frequencies.

There's lots to learn, lots to explain, and I'm more than willing to help, but a lot of things simply cannot be done and understood with Omnimic/XTZ and now with Plug-N-Play USB MIC options available for under $100 and at the most another few bucks for an adapter most people already have, there truly isn't any reason I can see to use anything but REW. YMMV of course.

--J

PS If anyone wants more specific links to RatShack/Monoprice on exactly which adapter to buy or any other info of any kind, feel free to ask here or PM.

Wow, that's great! Does using HDMI output complicate creating a correction file for the "sound card"?

I created a correction using a Pre-Out connection on the AVR - with all processing disabled. So in theory the graphs should show the combined effects of processing(once re-enabled), power-amps, speakers, room, microphone(accounted for with mic cal file).

The beta REW with ASIO support and a suitable driver such as ASIO4ALL allows you to select a single input channel such as the Centre channel, then you connect an RCA to 3.5mm lead between Centre Out (Pre-out) and feed that back to the laptops analogue input, acting as the loop back. Adjust the levels as appropriate and make the correction file.

If you want to check, just select another output channel and move the RCA as well, and check that the correction is still valid. Job done.

The actual sweep testing only requires the single HDMI, but the initial loop back requires the RCA lead.

A great post Jason - thanks. I may still be tempted (your argument is very seductive). What would I need as an external soundcard to connect to my prepro? Can you recommend one? Is it OK to connect that to the front AUX connector on my prepro? I would need a long lead as my hardware is in a closet outside the HT - what sort of lead would this be? Thanks for you help.

3. In the Output dropdown menu now you will see 8 selectable channels!! Oh, yeah!! So far, so good! I'll have to find out a way to rename them, coz the channels are just numbered 1-8, anyhow in my set up it is:

1: FL

2: FR

3: CC

4: Sub

5: SL

6: SR

7: FL Height

8: FR Height

Now choosing any of these numbers will direct the test signal to the appropriate speaker.

And now:

"Timing Reference Output" dropdown menu will show the same channel number. Clicking #4 will add the sub to that specific speaker.

Cream on the cake: the Denon AVR display shows: "Multi CH IN + PL IIz" and all 8 input indicators are lit!!!!!

You do not need any external sound card if using a USB Mic because you no longer need full duplex capabilities since you won't be using the sound card for "input" (that will be the USB Mic now) at the same time as "output." The output is all you'll be using on the sound card and I haven't seen a PC/Laptop since about 1997 that doesn't have a built-in sound card, so I'm sure you don't have to purchase anything but the Mic which is less than $100.

You will NOT need an "external" sound card. I'm SURE your PC/Laptop has a sound card and the one that is built-in is more than adequate if manufactured in the last 10 years or so. Promise! (My business is computer hardware/software, sales and service, in business since 1994, so I'm sure of this)

Yes, the front AUX is exactly what I use. If you want "easy" (actually, every method is very easy, but this is the long-term/in-use tried and true method) and only care about the front 3 channels as far as testing goes, then you can use a simple RCA cable, and 25' or so is fine, but I wouldn't go more than 50' max, and stay as close to 25' as possible.

Monoprice makes great ones and you can do the same for even less. All they do is use standard RG-6 Sat/CATV cable and put some RCA plugs on the end. I make my own for even less, but if you don't want to fool with it and don't need custom lengths, their prices cannot be beat.

You'll simply plug the mic in to your PC/Laptop (Up to 15' standard USB extension cable can be used and if you need longer than that, Monoprice again has wonderful and cheap options for amplified USB cables for much longer lengths) and then from the sound card in the same computer you'll run an RCA cable back into your pre-pro's AUX input.

That's it!

If you want access to all channels for testing (the only program that does this, for free or any reasonable amount of money at least) then you'll need a PC/Mac/Laptop with HDMI. You'll simply plug the Mic in to the USB port, same as the other example, and then run an HDMI cable from your computer to your pre-pro.

There are no other cables/connections required. Then simply download the driver from the link Jeff posted above, install it (can't mess this up - anyone can do it...Just click next next finish) and you're good to go.

I'm honestly not trying to make this sound any easier or more difficult than it is.

Well, I'm intrigued with being able to test 8 channels, which is why I went ahead and ordered the USB mic. But with the "old" method, I could individually test front left, front right, center (setting mono signal configured as PLII Cinema), and the subs. TBH, measuring the surrounds, heights, and wides is not likely to produce very meaningful information.

I feel it important to let everyone in on a few things as there are some differences in the two options.

While this information needs to go in the new thread since folks are starting to spend their hard earned money, I didn't feel it appropriate to wait.

Please forgive the off-topic post. I'm only trying to help folks decide how to spend their money.

First, I have recommended the UMM-6 USB Mic over the Mini-DSP for a few reasons. The most important reason is that for the same price (within a few dollars) you can get a true individually calibrated Mic with 0/45/90 degree axis and Polar Response data, from a Company in the US who also has great support if needed.

However, the current beta version of REW doesn't have the same total/100% PNP support for this Mic like it has for the Mini-DSP Mic.

BOTH Mics will hook up the same way, the same minimal amount of cabling, etc, but there will be a few more settings to select and set up in your PC and in REW if you purchase the UMM-6 Mic.

For folks that want a no nonsense, easy, and 100% PNP setup to be up and running with REW in 2 minutes, as of the time of this post, you need to purchase the Mini-DSP Mic.

In fact, as of right now, the Mini-DSP Mic is the only Mic that is in stock.

You can always send the Mini-DSP Mic off to Herb at CSL and have it calibrated later, and once we get more samples of them and compare the mics and the calibration files they come with from the factory we "may" find this isn't even necessary as they "may" be close enough.

I am in talks with JohnM, the author of REW and in fact just sent him a PM over at HTShack before posting here, asking if he could/would please add the same support for the UMM-6 Mic that he has added for the Mini-DSP because quite frankly for all you can get with the UMM-6 as far as the calibration goes, and the 0/45/90 degrees plus the Polar Response data for the same price, it's a much better bargain.

However, I do understand folks with not much PC experience who are coming from Omnimic/XTZ and who want a simple/no-nonsense PNP solution may be a bit frustrated with me if they get the UMM-6 Mic and can't just plug it in and go.

I'm not trying to dissuade anyone from purchasing the UMM-6, but again, if you are going to be disappointed if you have to do anything or set anything other than plugging it in, please order the Mini-DSP!! For now, it's your only choice anyway as the UMM-6 is out of stock.

Hope I haven't confused anyone or turned anyone off of REW or the UMM-6, but I felt it necessary to offer full disclosure as to the situation as it stands at this moment.

When I hear back from JohnM I will let you all know.

While I cannot commit for him or speak for him, I don't feel it will be a big deal to add the UMM-6 to the dropdown list and make it a selectable item just as he has done for the Mini-DSP, but again, as of this moment, there is a bit (just a bit, honest) more involved in getting up and running with the UMM-6 Mic.

Thanks for listening, and again, I hope to have all this moved over to a new thread very soon and invite you all there!!

I am not frightened away by the prospect of a little more effort getting the UMM-6 working with the new REW release. I like the idea of an individually-calibrated mic (like my EMM-6 fromSpectrum Labs). So, I am likely to keep my order as is for now. Since they are on back order, and since I am in no particular hurry, there is always time to change my mind as our discussions progress. (Jerry)

Regarding the new thread, here are my thoughts regarding the purpose of the thread:

- To assist existing REW users in reducing the complexity of their kits by providing guidance in implementing plug-and-play USB mics.

- To alleviate the apprehensions of those who don't use REW--it's not as difficult as it looks!

- To explore the uses and advantages of using HDMI connectivity and measuring speakers other than LCR and subs.

- To provide basic guidance for using REW measurement techniques to users of Audyssey RC, e.g. using REW to optimize speaker placements/room treatments prior to running RC, and to assess the post-calibration results.

- To provide a forum for sharing REW measurements for feedback and recommendations.

Sure! After re-reading what I typed, I can see how it may be a bit confusing.

Before I begin, I must re-state that I am in talks with JohnM the author of REW and as soon as I can get him a UMM-6 mic (they're on backorder right now) I believe he will put it in the drop-down list of supported/PNP mics in a new beta release.

I cannot guarantee this or speak for him, but I do feel he is responsive to this and very willing to accommodate as soon as he can get his hands on one. He's in Europe and so I have to get one and ship it to him, but will do this as soon as they are available again hopefully at the end of this month.

Now, the differences are few, but there are differences.

First, strictly speaking about setup of the two mics in REW, if you get the Mini-DSP mic, you will literally just fire up REW and in the preferences page you'll select the Mini-DSP mic as the mic you're using. At that point it will automatically ask you for the path to your calibration file that came with the mic. That's it! You're set up and ready to go.

If you get the UMM-6 mic, you will have to manually load the calibration file(s) that Herb sends you, which is literally the matter of a few extra clicks.

However, there is one more step with the UMM-6 mic (at this time). You must ALSO set the mics SPL readings (calibrate the mic) against an SPL Meter. As long as you have an SPL meter (any kind will work and the most common is a RatShack model) you're good to go.

The cool thing about the Mini-Dsp Mic is the SPL calibration data is already loaded in REW for this mic. So no SPL meter is necessary.

As long as you have an SPL meter though, it is an extremely easy/simple process and REW literally walks you through each step. When you go into preferences to set your inputs/outputs (mic/speakers) you will be reminded to calibrate the SPL and it will walk you through each and every step and offer help/a tutorial along the way with each step spelled out.

It literally takes less than five minutes to set up the UMM-6 Mic but it takes less than 5 seconds to set up the Mini-DSP mic.

In the interest of being complete, I'll also identify the differences in the mic's again.

The prices are the same within a few dollars either way.

The BIG difference is the UMM-6 Mic is hand calibrated against a specific reference mic at 0, 45, and 90 degrees by a human who knows his stuff and takes his time. He gives a detailed report of what he's done and each calibration file is separate and easy to load.

The Mini-DSP Mic is "supposedly" calibrated, but they don't specify any details other than that it is only calibrated to 0 degrees. What this means is, when taking measurements, you will point the mic towards the speaker, or in the case of taking a measurement of the L/R speakers plus sub, at the same time, you'd point it towards the center channel.

This doesn't compare well to the way we take Audyssey measurements, at 90 degrees, by pointing to the ceiling.

So... If you don't mind a few extra steps and have (or have access to) an SPL meter, the UMM-6 Mic is clearly the way to go, especially for all you get for the same price.

However, if you want quick and easy, plus if you don't want to wait, as the Mini-DSP Mic is in stock and ready to ship as of the time of this post, you can get that mic and do measurements at 0 degrees "calibrated" or you could still perform 90 degree measurements, but make sure you do NOT load the calibration file when you do that.

Condenser mics are pretty accurate except for the very low lows and very high highs most of the time, so this isn't necessarily a "huge" deal unless you need absolute accuracy or really want to know exactly what's going on.

For comparative measurements only, you cannot go wrong with either one.

You can always send the Mini-DSP Mic back to Herb at CSL at any time to have him do a calibration on it for a nominal fee, so if you do want quick-n-easy and don't want to wait, that may be a good option to get started.

As an FYI, I will be installing on an 2-3 year old Netbook with a standard RCA mini jack output, so will be running mini-to-stereo RCA to my receiver's AUX IN front analog input. I'm fine with just measuring the front speakers + sub so it looks like all I need is the USB mic and I can be up and running?

Oops, forgot to answer this other question...

You will need an RCA cable and a 1/8" (3.5mm) male to 2 RCA female splitter or y-cable.

You can get these at Radio Shack for about $5.00 or Monoprice for about $1.00.

You will plug that into your line out connection on your Netbook then plug ONE RCA cable into the splitter/y-cable and the other end into the AUX connection on your AVR/Pre-Pro leaving the other RCA jack open/not used.

That's it! It's that simple. You'll be able to easily run measurements on your L/C/R speakers this way.

I'm sure many of you are aware of this thread here on AVSForum: New mic option from the good people at Minidsp

Just in case someone missed it.

Thanks, Feri. All things considered, this seems like a better option due to the built-in PNP, at least since REW support is something the MiniDSP folks are aware of. For us "laypeople", can someone explain what the practical consequences of the UMM-6 having "truly individual calibration", 0/45/90 degree axis, and Polar Response (as per jevansoh) would have over the UMIK-1, if anything, for typical use on a mic stand?

Looking forward to working with our new room assessment paradigm some time in February

(not that REW is that new, but being on the ground floor of an evolving "best practice" methodology for pre and post-Audyssey (Pro) runs is exciting - hopefully I won't "REW" the day I did this, pun intended)

Hi Stuart, just responded to your PM.

To answer your question in more detail, please see my response to Batpig a few posts up.

The short answer is...It could be a big deal.. The Mini-DSP Mic only comes with 0 degree calibration, and even that is subjective as to how accurate it is.

So if you point the mic towards the ceiling (90 degrees) to compare with the way you take your Audyssey measurements then you must not use the calibration file it comes with.

If you order the UMM-6 and have an SPL meter (to use only ONE TIME for the initial setup, so borrowing one works great in this case and is the only other step to use it in REW instead of the Mini-DSP mic where you don't need to do this step) you will get a calibration file for 0, 45, and 90 degrees and can take all kinds of different measurements/positions.

How do the microphones themselves compare? Assuming built-in support will come for the UMM-6 in REW, which mic would be the better choice?

These products are both pretty new, so they haven't been out long enough to compare DOA or defective rates and build quality looks to be the same.

Condenser mics in general are actually pretty accurate out of the box and great for comparative measurements (the calibration file(s) are for absolute measurements for those of us who are picky enough to want to know exactly, down to a db or so what is going on) in all but the lowest and highest frequencies.

They both come with a carrying case and are both about the same size.

There is one potential caveat with the Mini-DSP Mic though.

If you have a problem with it, it will cost more and take longer to resolve as the Mini-DSP Mic is shipped directly from Hong Kong whereas the Dayton UMM-6 Mic (similar to the one that comes with Omnimic, if not the same) ships from the USA.

As far as "better choice" goes, it depends... Like most things, you have to pick which features/options you want.

If you aren't exactly "computer literate" or are scared of new things, then get the Mini-DSP Mic.

However, if you don't mind just a few more clicks and can follow very well written tutorials/guides and also have access to an SPL Meter to use just one time, then the UMM-6 Mic is my choice as it comes with a very accurate calibration at 0, 45, and 90 degrees for the same money and ships from the US.

Stereo mini-jack on one end, with two RCA connections on the other end. Male to male.

Do I still need a splitter? If so, why? Do you not want the connection to be stereo?

batpig's "Denon-to-English Dictionary"

Not Jason, but REW outputs a mono signal. The splitter takes the mono feed and allows you to feed both the left and right AUX IN audio connectors on the front of the AVR so that you can measure Left + Right signals with the AVR set to stereo. With the AVR set to PLII Cinema, you can measure the center channel. And you can unplug one side of the Y-cable to measure the Left or Right channel independently.

Well Jerry, ...with the HDMI cable hooked up from laptop to AVR/AVP and ASIO4ALL assigned to REW the whole concept becomes much more user friendly, i.e. you can select any speaker in a multi-channel setup individually, be it a front left, a center channel or a surround speaker, all up to 8 channels. I'm already there with my REW setup, I can send out a test signal from REW Generator to any speaker at will. Moreover, I can select "any speaker + sub" in the same above setting.

Isn’t it important to measure the combined output of the main speakers plus sub? That is what we hear when we listen. I'm not challenging you, Sanjay - just asking. Hopefully, this is the sort of thing that will be explained/discussed in the new REW thread.

I should have clarified: by 2 channels, I meant (for example) L+R simultaneously. If it is important to know how those channels interact, why don't room correction systems measure and correct for the interaction rather than each speaker? Notice that Audyssey does this for the interaction of a pair of subs but not a pair of speakers.

Stereo mini-jack on one end, with two RCA connections on the other end. Male to male.

Do I still need a splitter? If so, why? Do you not want the connection to be stereo?

You're very welcome, BP. I only wish I could respond more quickly. I know what it's like getting excited about something and having to wait on an answer.

I'm going to try to do better and rearrange a few things where I can get on this thread earlier each day while others are still awake and more actively participating which will hopefully reduce the time between questions directed towards me and my answers.

That splitter would only work if you had a male to female RCA cable.

I recommend one that has the same 3.5mm plug but instead of 2 RCA Male plugs it's 2 RCA Female jacks so you can use a standard male-to-male RCA cable.

You only want to use ONE RCA cable from this jack to your AVR/Pre-Pro because the signal is mono.

I hate to complicate things this early on, but... "IF" you wish to run a test on both speakers and subs at the same time to measure how everything is playing together once you're all done configuring Audyssey, with room treatments, etc to see the final response, then at the Pre-Pro end, where you plug the one cable into your AUX input, you can get another Y-Adapter which will have One Female RCA jack to TWO RCA Male Plugs to plug into both the Left and Right on your Pre-Pro.

That's how I have mine set up, FYI.

Hope this helps, sorry for the delayed response, and hopefully I didn't confuse you any more.

Well Jerry, ...with the HDMI cable hooked up from laptop to AVR/AVP and ASIO4ALL assigned to REW the whole concept becomes much more user friendly, i.e. you can select any speaker in a multi-channel setup individually, be it a front left, a center channel or a surround speaker, all up to 8 channels. I'm already there with my REW setup, I can send out a test signal from REW Generator to any speaker at will. Moreover, I can select "any speaker + sub" in the same above setting. (Feri)

YES!

This truly does simplify things so greatly, i actually recommend this type of setup if at all possible.

Not only is this the simplest setup and a true plug-n-play setup, but it's much more powerful, in being able to measure every channel.

You literally only need the USB Mic plugged in and one HDMI cable plugged in from your computer to your AVR/Pre-Pro and that's it.

You should always measure L + Sub, then R + Sub, and overlay them to make sure they're the same. If the response differs by much, you have issues that you need to resolve either via speaker/listening position placement/movement or via room treatments.

This should be done with Audyssey OFF.

Then, when all done, and with Audyssey turned back on, it's good to do a "Final check" with L+R+Subs.

Center+Sub by itself is also good, but shouldn't be combined with L/R or L+R+C at the same time.

If this is OT, let me know where better to post:
I am still deciding between OmniMic (OM) and REW for purposes of tweaking Audyssey Pro (including distance tweaks), optimizing sub placement and evaluating potential room treatments (but not for DIY speaker or subs).

Perhaps someone could comment on how this latest REW innovation affects that purchase decision for the uninitiated?

Correct me if I'm wrong but prior to this, OM had the ease-of-use advantage as it was basically plug in the usb mic and start measuring. So OM had a less steep learning curve for hardware, and perhaps was more software user-friendly as well. But REW may have had an advantage irt sophistication and flexibility (and that almost always means a steeper learning curve).

Subscribed.
If this is OT, let me know where better to post:
I am still deciding between OmniMic (OM) and REW for purposes of tweaking Audyssey Pro (including distance tweaks), optimizing sub placement and evaluating potential room treatments (but not for DIY speaker or subs).
Perhaps someone could comment on how this latest REW innovation affects that purchase decision for the uninitiated?
Correct me if I'm wrong but prior to this, OM had the ease-of-use advantage as it was basically plug in the usb mic and start measuring. So OM had a less steep learning curve for hardware, and perhaps was more software user-friendly as well. But REW may have had an advantage irt sophistication and flexibility (and that almost always means a steeper learning curve).

Take a look at the last dozen pages on the Audyssey thread and you can see good detail on your question. I ordered the mini USB mic and it is in my office, so I went with the PNP option and we will see what happens.

If this is OT, let me know where better to post:
I am still deciding between OmniMic (OM) and REW for purposes of tweaking Audyssey Pro (including distance tweaks), optimizing sub placement and evaluating potential room treatments (but not for DIY speaker or subs).

Perhaps someone could comment on how this latest REW innovation affects that purchase decision for the uninitiated?

Correct me if I'm wrong but prior to this, OM had the ease-of-use advantage as it was basically plug in the usb mic and start measuring. So OM had a less steep learning curve for hardware, and perhaps was more software user-friendly as well. But REW may have had an advantage irt sophistication and flexibility (and that almost always means a steeper learning curve).

I was of a similar mind to you SoM. I bought the OmniMic and it really is as easy to use as everyone says. This was especially important for me as I am not really Windows-literate any more (over 10 years since I used Windows). OM is easy to set up (1 minute tops) and just as easy to use. You would be measuring 5 minutes after opening the box. I have found it a great introduction to the world of measuring and, as you know, it has helped me enormously - first in finding that phase problem with my subs, then with optimising the splice and latterly with getting a nice flat response after installing my dual Submersive F2s, not to mention numerous smaller tweaks.

HST I am waiting for delivery of my UMM-6 mic and have already downloaded the REW beta and the ASIO driver.

What tempts me to REW is the fact that it is now more or less PnP. I will have a USB mic plugged into a USB port on my Windows laptop and a single HDMI cable from the laptop to the front HDMI port on my 5509. With Jason's guidance I expect to be set up and measuring in 15-30 minutes from get-go. Additionally, REW can do quite a lot more than OM, which also appeals. I especially like the idea of doing one measurement and then looking at it and graphing it in all sorts of different ways. I also like the idea that I can send the 'raw' REW file to someone more experienced and they can analyse it for me. Also, I feel the support will be much better for REW han for OM, especially with Jason's help in this thread, along with REW 'old timers' like Jerry. There is an OM thread on AVS but I haven't found it to be all that helpful - half of it is concerned with speaker design for example which is of zero interest to me.

So, as you say, OM has a less steep learning curve and more user-friendly s/w but REW is more sophisticated and flexible. The fact that REW has a steeper learning curve has evaporated as a problem for me since Jason kindly stepped in and offered to start and support this thread. I know from Jerry how much Jason's help means and I am sure that the learning curve will no longer be an issue. I am even looking forward to it! Most of this has been influenced by the simple two lead connection now available with REW. Even I can plug a mic in to a USB port and am HDMI cable in to the AVR!

Finally, there is also the issue of cost for a first time user. OM costs about $300, complete. REW will cost about $90 (for the mic) and the rest is free. That alone will be enough to sway many people - the price of entry just dropped by $200! And if REW turns out to be not to your liking, I bet you could recoup over half the investment by selling the CSL calibrated mic in the classifieds.

Subscribed.
If this is OT, let me know where better to post:
I am still deciding between OmniMic (OM) and REW for purposes of tweaking Audyssey Pro (including distance tweaks), optimizing sub placement and evaluating potential room treatments (but not for DIY speaker or subs).
Perhaps someone could comment on how this latest REW innovation affects that purchase decision for the uninitiated?
Correct me if I'm wrong but prior to this, OM had the ease-of-use advantage as it was basically plug in the usb mic and start measuring. So OM had a less steep learning curve for hardware, and perhaps was more software user-friendly as well. But REW may have had an advantage irt sophistication and flexibility (and that almost always means a steeper learning curve).

Take a look at the last dozen pages on the Audyssey thread and you can see good detail on your question. I ordered the mini USB mic and it is in my office, so I went with the PNP option and we will see what happens.

Or at post 10 here where all the relevant posts from the Audyssey thread have been copied across. ;)

Take a look at the last dozen pages on the Audyssey thread and you can see good detail on your question. I ordered the mini USB mic and it is in my office, so I went with the PNP option and we will see what happens.

Yeah, probably the biggest advantages here are:

1. Once the MiniDSP UMIK-1 usb microphone is plugged into the laptop REW will simply suck in the mic's calibrations file.
2. Latest laptops with HDMI will allow in conjunction with ASIO4ALL driver to turn REW into an 8 channel monster letting the users send test signals to any speaker in the system or any two (like L+sub).

2. Latest laptops with HDMI will allow in conjunction with ASIO4ALL driver to turn REW into an 8 channel monster letting the users send test signals to any speaker in the system or any two (like L+sub).

I am amazed that I am so excited at the prospect of this :)

I am hoping Jason (or anyone) might create a step by step guide as to what we need to do, once REW is set up and working, so that we can get started right away on the most important measurements, how to interpret them and what changes we might make as result of seeing them.

I am hoping Jason (or anyone) might create a step by step guide as to what we need to do, once REW is set up and working, so that we can get started right away on the most important measurements, how to interpret them and what changes we might make as result of seeing them.

Keith, have you downloaded REW and ASIO4ALL, yet? I suppose so. Then, while waiting for the deep dive into important measurements why not try your wings by clicking on Generator and see how you can steer around in your speaker system, one by one with some test tones or log sweeps via a simple listening test. It's fun to get acquainted with the bells and whistles of REW.

I am hoping Jason (or anyone) might create a step by step guide as to what we need to do, once REW is set up and working, so that we can get started right away on the most important measurements, how to interpret them and what changes we might make as result of seeing them.

+1 - Just placed my order for the UMIK - ready to take on the challenge of in room measurement, and more importantly figuring out how to add room treatments, move speakers, etc to achieve maximum results.

What tempts me to REW is the fact that it is now more or less PnP. I will have a USB mic plugged into a USB port on my Windows laptop and a single HDMI cable from the laptop to the front HDMI port on my 5509. With Jason's guidance I expect to be set up and measuring in 15-30 minutes from get-go. Additionally, REW can do quite a lot more than OM, which also appeals. I especially like the idea of doing one measurement and then looking at it and graphing it in all sorts of different ways. I also like the idea that I can send the 'raw' REW file to someone more experienced and they can analyse it for me. Also, I feel the support will be much better for REW han for OM, especially with Jason's help in this thread, along with REW 'old timers' like Jerry. There is an OM thread on AVS but I haven't found it to be all that helpful - half of it is concerned with speaker design for example which is of zero interest to me.

So, as you say, OM has a less steep learning curve and more user-friendly s/w but REW is more sophisticated and flexible. The fact that REW has a steeper learning curve has evaporated as a problem for me since Jason kindly stepped in and offered to start and support this thread. I know from Jerry how much Jason's help means and I am sure that the learning curve will no longer be an issue. I am even looking forward to it! Most of this has been influenced by the simple two lead connection now available with REW. Even I can plug a mic in to a USB port and am HDMI cable in to the AVR!

Finally, there is also the issue of cost for a first time user. OM costs about $300, complete. REW will cost about $90 (for the mic) and the rest is free. That alone will be enough to sway many people - the price of entry just dropped by $200! And if REW turns out to be not to your liking, I bet you could recoup over half the investment by selling the CSL calibrated mic in the classifieds.

Hope this has helped in some way.

Look on the bright side, Keith: you won't be alone in learning REW (and in some of our cases, unlearning measurement approaches that are measuring what the experts call interference vs. what the more 'heuristic' minded among us thought was combined response).

Agreed about OM: it was very easy to use OOB, but when I started measuring to access Pro cals, your graphs on the Pro thread during your phase adventure were the only hands-on example I had to work from. I didn't find much direction from the OM thread about best practice workflow or configurations that weren't appropriate to test (e.g. LCR vs subs) from an acoustic model POV. So in that sense, REW and Jason's thought leadership will be filling in a critical gap in how room correction methodology should be pursued by the audio enthusiast from a less rigorous technical background. In particular, how to best use room treatments judiciously, given WAF and physical limitations of the HT room, to drive the process. We all can't be Sanjay or even you, but we can learn by example .

Oh well...life would be boring if we weren't needing to reboot our thinking every few years .

I have personally been able to get my dedicated theater within +/- 4db with NO Audyssey unsmoothed, and within +/-2 db with 1/3rd smoothing all the way from 20hz-20khz but have realized over the last year or so that frequency response is NOT at all, not even close, to being what is very important.... It's the modal decay times in the low frequencies and the ETC in the upper frequencies.

+1

I mention it often, here's a recent post of mine;

"Considering everything I discovered over the past several decades in audio, I kow that superb audio, is all about the room. And the room, is all about the time domain.

The perceived quality of us experiencing playback at realistic levels, and higher, does depend on the time domain. How the decay characteristics over time, at various frequencies, combined with nasty clarity smearing early reflections, all manifest into how tolerable a particular playback level will be. All too often I see countless equipt. racks, inappropriate boundary surfaces, display panels, etc, all playing a negative role in the energy coming off our painstakingly designed/built/purchased speakers,...before it even has a chance.

The loudspeaker end of the room, and the space immediately between the LP and the speakers, is so damn important. That fact, plus, ... and more relative to this discussion, the overall decay of the room, plays a overwhelming role in how we perceive reference level.

I know acoustics isn't as sexy as loudspeakers and subs, but it's where the gold is."
Problem is, mentioning acoustc distortions, in DIY louspeaker and sub forum, just doesn't get much traction.

I like AVS, I prefer AVS over the other forums I frequent, but it is all too often deficient with regard to good, solid, acoustic discussions rooted in the well vetted science and work of the industry greats. Yes, there's good acoustics info and discussions here, but not the solid exchange of information in an environment conducive that allows said info to flourish. So these efforts are very much applauded.

The focus here is REW, regardless,..any optimization strategy is flawed if not incorporating measurement verification for all efforts.

how can the time reference loopback connection be made when a USB microphone is used?
also, is the initial sound card calibration still needed/valid given that the input signal does not go through the soundcard analog stage ?

I am hoping Jason (or anyone) might create a step by step guide as to what we need to do, once REW is set up and working, so that we can get started right away on the most important measurements, how to interpret them and what changes we might make as result of seeing them.

Keith, have you downloaded REW and ASIO4ALL, yet? I suppose so. Then, while waiting for the deep dive into important measurements why not try your wings by clicking on Generator and see how you can steer around in your speaker system, one by one with some test tones or log sweeps via a simple listening test. It's fun to get acquainted with the bells and whistles of REW.

Oooh... no I haven't tried this. I wondered if I needed to wait till I had the mic before loading up REW. Yes, I downloaded REW beta and ASIO, so I will give this a try tomorrow. Thanks. Feri.

Look on the bright side, Keith: you won't be alone in learning REW (and in some of our cases, unlearning measurement approaches that are measuring what the experts call interference vs. what the more 'heuristic' minded among us thought was combined response).

Agreed about OM: it was very easy to use OOB, but when I started measuring to access Pro cals, your graphs on the Pro thread during your phase adventure were the only hands-on example I had to work from. I didn't find much direction from the OM thread about best practice workflow or configurations that weren't appropriate to test (e.g. LCR vs subs) from an acoustic model POV. So in that sense, REW and Jason's thought leadership will be filling in a critical gap in how room correction methodology should be pursued by the audio enthusiast from a less rigorous technical background. In particular, how to best use room treatments judiciously, given WAF and physical limitations of the HT room, to drive the process. We all can't be Sanjay or even you, but we can learn by example .

Oh well...life would be boring if we weren't needing to reboot our thinking every few years .

+1 to all that. I have room treatments now, but they have been placed by following recommendations rather than by relying on measurements. Chances are they are OK but it will be nice to verify this once I get started on REW. Am also looking forward to running REW tomorrow* per Feri's suggestion and getting to know the menu layouts etc.

Am off to watch Die Hard 2 now (from the BD box set. I am having a Bruce week :)

"Considering everything I discovered over the past several decades in audio, I kow that superb audio, is all about the room. And the room, is all about the time domain.

The perceived quality of us experiencing playback at realistic levels, and higher, does depend on the time domain. How the decay characteristics over time, at various frequencies, combined with nasty clarity smearing early reflections, all manifest into how tolerable a particular playback level will be. All too often I see countless equipt. racks, inappropriate boundary surfaces, display panels, etc, all playing a negative role in the energy coming off our painstakingly designed/built/purchased speakers,...before it even has a chance.

The loudspeaker end of the room, and the space immediately between the LP and the speakers, is so damn important. That fact, plus, ... and more relative to this discussion, the overall decay of the room, plays a overwhelming role in how we perceive reference level.

I know acoustics isn't as sexy as loudspeakers and subs, but it's where the gold is."

Absolutely. It is interesting that you mention listening levels. I've found, since treating my room, that I can listen at seemingly endless levels on the MV, in total comfort, even though the SPL meter is telling me that it is way too 'loud' really. It is just so clean and undistorted.

Let's hope this thread doesn't get hijacked by endless bickering, as so many of the acoustic threads seem to. I am sure it will be a terrifically valuable resource.

Oooh... no I haven't tried this. I wondered if I needed to wait till I had the mic before loading up REW. Yes, I downloaded REW beta and ASIO, so I will give this a try tomorrow. Thanks. Feri.

Now, if you engage channel #4 the test signal will be routed to your subwoofer channel in the AVP. If you set the Generator to Log Sweep and start from 10 Hz say up to 200 Hz and set a duration of 60 seconds, you will be able to carefully hear by ear how your subs perform and at what frequency they start to kick-in.. But most interesting will be to hear the rattling of "stuff" in your room. You can determine the resonance frequency of your "stuff", and take measures to get rid of them. How to get rid of them is another story, maybe a "rattling stuff" forum can help.

Thanks for setting this thread up. When I get home, I'll try using REW with HDMI with my existing setup (what?! No need to contort behind the avr to connect REW?).

I'll admit, I ordered the UMM-6 too. Not needing to hookup the EMM-6 to the soundcard and the soundcard to the laptop and the thigh bone to the hip bone, the hip bone to the...
will make things a LOT simpler.

First of all, thanks to Jason for being the thread-starter, and for providing a nice introduction to what I hope will be interesting and productive discussions. And second, thanks to Keith for transferring the useful posts from the Audyssey thread, and for volunteering to help assemble and maintain a FAQ. Guys, I want to help as well--please let me know how I can contribute.

In addition to learning how to simplify my REW kit with the USB mic and HDMI connection (which will need to wait until the UMM-6 is shipping), here are examples of what I hope to get out of this thread. Here are two recent measurements of my system, a waterfall and an ETC:

I can generate these graphs, but here are the uncertainties:

- Did I configure the graphs properly? Are the horizontal and vertical scales set properly? What are the various settings in the "Controls" panel for each type of graph? (Amir, who I see has already provided a link to his thread over on the WhatsBetterForum.com, provides some good examples of how to configure Waterfalls, but I'm not sure I understand it all. BTW, welcome, Amir!)

- How should the speakers be configured before taking these measurements? Do I measure one speaker at a time for ETC? Does the waterfall need all subs as well as the main speakers in the measurement? Is Audyssey on or off? Do I take measurements only at the MLP, or at several spots in the room?

- What do the graphs show? Does the Waterfall show any resonances that need to be looked at, or does the graph show something that is "good enough"?

- It's easy to see the reflections in the ETC graph. Are the reflections significant enough to warrant treatments? Should all the peaks be below -20dB? There are two early reflections at 7m and 11.3m. How can I tell which surfaces in my room are causing these reflections?

- Once I know what I am looking at, what are the various methods to address the problems? Should I go out and buy a roll of pink fluffy? ;)

I figure that once I master these topics, I could start advertising my services as an audio consultant here in Austin!